Method of forming bolt heads



Dec. 21, 1937. H. CADWALLADER, JR 0 METHOD OF FORMING BOLT HEADS FiledJune 2, 1937 INVENTOR Patented Dec. 21, I937 METHOD oF FORMING BOLTHEADS Harry Cadwallader Jr., Philadelphia, Pa. Application June z,,1937, Serial No. 145,981

4 Claims.

The present invention relates to a method of making machine bolts andmore particularly to a method of forming the heads thereof. In boltheads as heretofore made by the drop forging method the partiallycompleted blank or completed bolt head requires considerable machiningsuch as grinding, trimming, and the like, to remove the fins and forgingangles which have been a necessary adjunct of the forming operations.Furthermoregby prior methods there has been no certainty that thev headflanges will be of the same thickness, and more often than otherwise oneis thin while the other is thick and .therefore an additional machiningoperation is necessary to complete thehead.

. Some of the objects of the present invention :are to provide animproved methodof making a vbolthead for a machine bolt; to provide amethod wherein thematerialfor the head is upset and gathered into apreliminary shape without the formation of fins; to provide a stepin'the method of making a bolt head wherein a second gathering operationis employed; to reduce the head to a second formed shape withoutproducing excess metal at the forging angles or forming fins there-I on;to provide a bolt head forming method where-- in the flanges of the headare of uniform thick- .ness; to provide a method wherein the head isformed partially in a die and partially in a' .punch of die shape, thetwo members coactin'g in sucha way as to provide a head shape with,-outfins; and to provide other improvements aszwill hereinafter appear.

In the accompanying drawing Fig. 1 represents an elevation of .one partof a two part die with the associated punches in part section asarranged to carry out two successive steps of the method of the presentinvention; Fig. 2 represents a front elevation of the die block; Fig. 3represents a front elevation of the punches; Fig. 4 represents a sideelevation of the bolt stock after the first gathering operation; Fig. 5represents a side elevation of the stock after the second gatheringoperation; Fig. 6 represents a diagrammatic plan of themechanism used inthe final operation; Fig. 7 represents a diagrammatic elevation of themechanism of Fig. 6; and Fig. 8 represents a perspective of the finishedbolt.

Referring to the drawing one form of apparatus for carrying out themethod of the present invention consists of a die block I0 which formsan anvil having preformed die shapes II and I2 by means of which twosuccessive operations are performed. The invention is not limited to theparticular single block construction here shown I as obviously twoseparate dies can be made to I serve the same purpose. The die shape IIis in the form of a frusto-conical socket I 3 opening into a cylindricalhole 14 of such diameter as will snugly receive the round rod or blank[5 upon which the head of the bolt is to be formed. A punch l6 mountedfor reciprocating movement towards and away from the front face of theblock Ill is provided and located to register with the die shape I3.This punch I 6 is pro- .vided with a forming head having afrusto-conicalsocket I! in the face thereof, the arrangement being suchthat when the punch 56 is .in face contact with the block I0 bases ofthe two sockets I3 and I1 will register one with another to form a dieormold having oppositely tapered end portions.

' The die shape l2 has agenerally rectangular socket opening into acylindrical hole 2| which is to receive the rod l5 or part which becomesthe shank of the finished bolt. Preferably the inner corners of thesocket 20 are rounded to give a more finished effect. A punch 22 mountedfor reciprocating movement towards and away from the front face of theblock I0 is provided and located to register with the die shape 20. Thispunch 22 is provided with a forming head having a frusto-conical socket23in the face thereof but which is of less depth than the socket I! andits volume is definitely calculated to receive approximately therequired amount of metal necessary for working into the head shape bythe final operation. a

Following the action of the punch 22, the partially formed bolt istransferred to a sliding head type of forging machine wherein the upsethead 24 is placed in position to be acted upon by a top slide hammer 25,a bottom slide hammer 26, and two oppositely disposed side slide hammers21 and 28. These hammers are reciprocated in .the well known manner ofsuch machines, the

action being such that the top and bottom ham- In carrying out the stepsof the present method a piece of round bar stock of proper length isplaced in a heated condition within the die H with the end upon whichthe bolt head is to be formed projecting outwardly from the face of theblock Ill. The punch I6 is now shot forward giving the end of the bar asharp blow and since this end has entered the socket l1 it will be upsetor gathered into a shape complemental to the two sockets l3 and IT. Thisis shown in Fig. 4 at 3B and 3!. Thus the preliminary step provides apartial head having a substantially smooth double tapered face minus anyfins or projections. Upon the withdrawal of the punch it the partiallyshaped blank is'removed and placed in the die 12, whereupon the punch 22is projected against the enlarged end and causes the tapered part 30 toflow into the socket 29 and form the same, while the part 3! which is inthe socket 23 is enlarged in diameter but shortened in length giving theappearance of the head as shown in Fig. 5 wherein the part 32 consistsof fiat sides spaced by the diameter of the shank and at its endsextending in both directions to merge into the frusto-conical part 33resulting from the gathering of the metal in the socket 23. Thus again amore complete blank is formed but without fins or other irregularitiessuch as are usually present in bolt manufacture. Following thisoperation the blank is again heated to forging temperature and placed inposition between the sliding hammers of the header forging machine wherethe head is worked into shape by successive blows of the pairs ofhammers and 26, and 2'! and28. These pairs as heretofore explainedoperate alternately, while the end hammer 36 operates simultaneouslywith each pair. This operation not only Works the head into finaldimensions and shape, but also does the work without producing fins orforgingangles which ordinarily would have to be removed. The resultingcompleted bolt is shown in Fig. 8 and it will be evident that it has asmooth machine finished appearance and has been produced without theordinary auxiliary step-s of machining and trimming. The threads 34which complete the bolt are cut in the usual manner and form no part ofthe present invention.

Broadly considered the steps by which the shapes shown in Figs. 4 and 5are formed may or may not include treatingbetween the two operations,because in some blank sizes the metal will hold its initial heatsufiiciently long to enable both steps to be carried out, but in othersizes it may be found necessary to reheat between these steps.

While but one form of apparatus has been shown in which this inventionmay be embodied, it is to be understood that the invention is notlimited to any specific construction, but might be applied to variousforms without departing from the spirit of the invention or the scope ofthe appended claims.

Having thus described my invention, I claim:

1. The method of forming a bolt head which consists in upsetting the endof a heated rod to form a head blank of double frustum shape, reheatingthe shaped blank and gathering the flowing metal to form a substantiallyrectangular base part having a frustum shaped head blank, reheating theblank, and hammering the sides and end of said head blank to form a bolthead of predetermined shape.

2. The method of forming a bolt head which consists in upsetting the endof a heated rod to form a head blank of double frustum shape, reheatingthe shaped blank and gathering the flowing metalto form a substantiallyrectangular base part having a frustum shaped head blank, reheating theblank, and alternately hammering the sides of the head blank in pairswhile hammering the end of the head blank.

3. The method of forming a bolt head which consists in placing a heatedrod blank in a fixed anvil die with an end projecting therefrom,striking the projecting end with a punch having a die socket to receivethe projecting end, removing the partially formed blank and reheatingit, placing the reheated blank in. another fixed anvil die with aportion of the formed head projecting therefrom, striking the projectinghead portion with a punch having a die socket to gather the projectingportion into a predetermined shape, removing the partially formed blankand reheating it, and then hammering the sides and end to the finishedsize and shape.

4. The method of'forming a bolt head which consists in upsetting the endof a heated rod to form a head blank of substantially double frustumshape, then gathering the flowing metal underpressure toform asubstantially rectangular partly curved base part having a frustumshaped head blank, reheating the blank, and hammering the sides and endof said head blank to form a bolt head of predetermined shape.

HARRY CADWALLADER, JR.

